St. Anselm, Archbishop of Canterbury (d. 1109 AD), often recognized for his ontological argument for the existence of God, coined the phrase in Latin credo ut intelligam, or "I believe so that I may understand." It is an intriguing proposition, and one on which I must admit to vacillating with regard to accepting. Still, I bring it up here to segue into the epistle to the Hebrews and use its formula as the basis for another proposition that encapsulates the thrust of much in Hebrews 3. Namely, I believe so that I may obey. As I have mentioned in a previous blog, sometimes there exists an extreme tendency in parts of Christianity to view belief and obedience as conceptually and practically antithetical. These are, clearly, distinct concepts. But, we do err if we fail to recognize the degree (however large or small that may be) of semantic overlap shared between these two terms, especially as it pertains to biblical usage. The intimate relationship between belief and obedience for those who are in Christ, with unbelief and disobedience as sharp contrasts, is clearly evinced in chapters 3 and 4 of Hebrews. The following examples illustrate these relationships:
1) We are to "take care" that we do not have an "unbelieving heart" (Hebrews 3:12)
2) God swore to those who were "disobedient" that they would not enter His rest (3:18)
3) Yet, their inability to enter was predicated on "unbelief" (3:19)
4) Those who "believe" enter into God's rest (4:3)
5) Those in the wilderness did not enter because of "disobedience" (4:6, 11; compare this with point  above)
6) Numerous exhortations toward particular actions implicate "obedience" (3:12, 13; 4:11, 14, 16)
The descriptions and exhortations found in these passages are entirely unambiguous: the Christian ought to seek, by the grace that God provides, to be characterized by belief and obedience. For, if we, as members of Christ's body, claim one then this will necessarily entail the other. Although we are by no means perfect, in terms of our aim neither obedience without belief nor belief without obedience profit anything. The question we might ask is why obedience is so important for the believer. The answer is that it relates directly to our identity in Christ.
This notion of Christian identity is made explicit in the phrase "For we have become partakers of Christ" (3:12). As Christians, we are claiming to be united with Christ, having been made one with Him by Him, partaking of His Body by "eat[ing His] flesh" and "drink[ing His] blood" (John 6:54). But this unification necessarily involves a process of transformation wherein we must be changed to be made more like Christ, the process that is typically termed "sanctification" by Protestants, and "deification" by Roman Catholics and Orthodox Christians (see John 17:21). As Jesus Himself declared, those who "come" to Him "will never hunger," and those who "believe" in Him "will never thirst" (6:35, emphasis added). Moreover, if we, drawn by the Father, "believe" in Jesus Christ, we will have "eternal life," and if we "eat" of His "flesh" and "drink" of His "blood" we will be granted "eternal life," for "the bread that [Jesus] give[s] for the life of the world is [His] flesh" (6:44, 47, 51). Therefore, believing in Him unto eternal life (that He both won and gives), consuming His body so that we are transformed by partaking of Him, has the effect that we abide in Him, and He in us (6:56).
At this point, especially as it pertains to the Johannine passage, we have clearly established that belief inheres to our identity in Christ, but what about obedience? Importantly, Jesus returns to the profound notion of "abiding in Him" when He is alone with His disciples before He goes to be crucified, in the section of John that is often referred to as "the upper room discourse" (John 13-17). After proclaiming that those who "believe" in Jesus "will do greater works" than He, and stating multiple times that if we truly love Him we "will keep His commandments," Jesus invites His disciples to both "abide in" Him and have Him "abide in" them (14:12, 15, 21, 23-24; 15:4). The language Christ uses harkens back to John 6, but, significantly, His invitation is related to both unification and the production of "fruit," which is obedience - "keeping" and obeying His words and His commands (15:4, 5, 10). Our claim to abide in Christ is validated by belief that produces obedience.
The lurking danger behind all this is our sinful propensity to see our obedience as a means of attaining righteousness rather than admitting to imputed righteousness through Christ. We must always remember that our ability to obey and our producing the "fruit" of good works and obedience is never purely our own. This not only keeps our pride in check, but it is an encouragement that we can be strengthened by, knowing that God Himself is granting us His ability to "work out [our] salvation with fear and trembling; for it is God who is at work in [us] both to will and to work for His good pleasure" (Philippians 2:12-13). This is why Paul writes to the church at Ephesus:
For by grace you have been saved through faith; and that not of yourselves; it is the gift of God; not as a result of works, so that no one may boast. For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them. (Ephesians 2:8-10)
Obedience and works do not save us, and even the faith we have is a "gift of God." This is why He alone is to be worshiped and glorified for the salvation that He wrought through Jesus Christ our Lord. But, we should never lose sight of the fact that "we are [God's] workmanship," and that He has "created [us] in Christ Jesus" with the object of obedience. And these works God Himself has "prepared beforehand"; all that is required of us is that we humbly "walk in them."
With these thoughts in mind, we return to the passage at hand in Hebrews 3:14-19. Prior to these verses, the author has explicitly urged the readership towards steadfastness and obedience in contrast to the example of unbelief and disobedience of the Israelites in the wilderness who were refused entry into God's rest, the Promised Land (3:6-11). Then, the writer cautions believers to guard against an "unbelieving heart" and "encourage one another" as co-members of the body of Christ. But why should we do such things? Why should we "encourage one another" so that we will not be "hardened by the deceitfulness of sin"? Essentially, because such hardening and disbelief is contrary to the reality that Jesus Christ has obtained for us now. Jesus became God in human flesh, He lived a perfect, sinless life, He suffered, bled and died, He rose again - all for the glory of the Father and to invite us to believe in Him so that we might abide in Him and, thus, obey Him in love: if we love Him, we will keep His commandments; if we keep His commandments, we will abide in His love (John 14:15; 15:10).
For this reason the author of Hebrews refers to a present reality: "we have become partakers of Christ" (Hebrews 3:14, emphasis added; see also 3:6). Still, this, too (as with verse 6), is paired with a conditional that pertains to obedience:
[W]e have become partakers of Christ, if we hold fast the beginning of our assurance firm until the end, while it is said, "Today if you hear His voice, do not harden your hearts, as when they provoked Me." For who provoked Him when they had heard? Indeed, did not all those who came out of Egypt led by Moses? And with whom was He angry for forty years? Was it not with those who sinned, whose bodies fell in the wilderness? And to whom did He swear that they would not enter His rest, but to those who were disobedient? So we see that they were not able to enter because of unbelief. (3:14-19)
If we are humble and willing to obey in love, knowing that it is not truly our own doing, but Christ in us, we will realize that we have been empowered to obey as a result of our identity in Christ. However, we must choose to obey in love, and we must choose "Today," so that we are not deceived by the intangible tomorrow that belongs to a temporal framework we are not guaranteed. "Today," the Holy Spirit is speaking. "Today," we hear His voice. "Today," we must not harden our hearts as those who "provoked" God in the wilderness, never to enter His rest. "Today," we must not be "disobedient." "Today," we must not be characterized by "unbelief." "Today," God is working in us to do these things - His good will and His pleasure - so that we might walk in the good works He has wondrously and beautifully prepared for us. "Today," we believe so that we might obey, and obey in love.